1. Field of the Invention
The present invention relates to a personal communication system, and in particular, to a communication system including portable terminals each having a personal call function and fixed terminals which can be connected to the portable terminals.
2. Description of the Related Art
In a conventional telephone system, each telephone set is assigned with a number (called a telephone number) such that when a user dials a telephone number of a telephone set on a call termination side from a telephone set on a call initiation side, a communication path is established between the telephone sets. This system however is attended with a problem, namely, when the telephone partner on the destination side is absent, the telephone call cannot be conducted.
In contrast to the system above, there has been employed a calling system called a pocket-bell system or a portable radio terminal system in which a person apart from the telephone set is notified that an attempt of a telephone call has been made to the telephone set. In the conventional system associated with the pocket bells and/or portable radio terminals, the person to whom the telephone call has been attempted issues a call to a predetermined telephone set to identify the call initiating person so as to thereafter dial a telephone number of the call initiator. In an improved version of the pocket bell system, the telephone number of the call initiator is displayed at the call issuance so that the person on the call termination side directly dials the Presented telephone number.
An improved communication system in which portable radio terminals and telephone sets are employed in combination has been described, for example, in the JP-A-60-103834 and the JP-A-61-94422.
In a personal call communication system described in the JP-A-60-103834, there are utilized a portable radio terminal manufactured in a form of a card to which a personal identification (ID) number of a card Possessor is assigned and a telephone set having a function to read, when the portable radio card is combined with the telephone set, information items such as the personal identification number therefrom. A call initiator dials, in a state where the portable radio card in linked with the telephone set, a telephone number of a call destination partner. The identification number of the call initiator and a call initiating telephone number read from the portable radio card and the telephone number of the call destination thus dialed are sent to a switch and then supplied therefrom to a central controller connected to the switch. The central controller has a table including correspondences between telephone numbers, identification numbers, and personal names so as to convert the call destination telephone number and the call initiator identification number into a call destination identification number and call initiator name, respectively The obtained number and name are broadcast through a radio wave to each portable radio card via a personal call unit (radio transmission station).
In each portable terminal or card, when the received call destination identification number matches the identification number of the portable terminal or card, the call initiator name from the personal call unit is presented on a display screen of the portable card; moreover, an audible signal is produced to notify the call to the card proprietor. On recognizing the call tone, the called person combines the card with a telephone set nearby, so that the identification number of the called person is read from the card and is then sent to a switch so as to be delivered to the central controller. The central controller has a call control table storing therein an identification number under a call and a telephone number of the call initiator. On receiving the identification number of the call destination person, the controller reads the telephone number of the caller from the call control table to establish a call or speech path between the call initiating telephone set and the call terminating telephone set.
In the communication system described in the JP-A-61-94422, when an identification number of a portable radio terminal as a call destination is dialed from a telephone set on a call initiation side, a telephone number of the call initiating telephone set and the identification number of the portable radio terminal are radio broadcast. When a call destination person connects, on recognizing the call, the portable radio terminal to a nearby telephone set, the telephone number of the call initiating telephone set is automatically transmitted so that the telephone set on the call initiation side is connected via a switch to the telephone set on the call termination side.